问题补充：
Is this the website you want to have into your files to help you learn English?
A. who; to add
B. that; add
C. whom; adding
D. that; added
答案：
A. who; to add
B. that; add
C. whom; adding
(答案→)D. that; added
解析：非谓语动词是英语中难度较大的语法项目之一，因而在定语从句中加入非谓语动词会增加考查定语从句的难度。对这类题目最有效的办法就是将句子还原。本句还原后应是：You want to have the website added into your files to help you learn English.先行词是the website, 因为在定语从句里做宾语，所以可以用that, which或者省略，但是第二个空只能用added， 因为还考查到了have something done， 这里是网站被添加到收藏夹。
